Table 5. Spectral Analysis of Hydrolyzed Products of PBNA Derivatives, Nitrophenol, and Dinitrophenol^a,b,c.

	observed m/z (Da)	proposed formula [fragmentation steps]	mass error (ppm)	abundance diff. (%)
nitrophenol MS1 ions	138.0196	C6H4NO3–	–0.72	0.00%
	139.0232	“M + 1” isotope	3.60	–0.77%
nitrophenol MS2 ions	108.0216	C6H4O2– [−NO]	–0.93	N/A
	92.0273	C6H4O– [−NO2]	5.43	N/A
	45.9939	NO2–	8.70	N/A
dinitrophenol MS1 ions	183.0048	C6H3N2O5–	0.55	0.00%
	184.0081	“M + 1” isotope	3.26	3.14%
	ND	“M + 2” isotope	ND	ND
dinitrophenol MS2 ions	153.0069	C6H3NO4– [−NO]	0.65	N/A
	123.0094	C6H3O3– [−NO, −NO]	4.88	N/A
	95.0135	C5H3O2– [−NO, −NO, −CO]	–4.21	N/A
	137.0123	C6H3NO3– [−NO2]	3.65	N/A
	109.0167	C5H3NO2– [−NO2, −CO]	–1.83	N/A

^aNitrophenol and dinitrophenol are detected as [M – H]⁻.

^bExamples of mass spectra: Figure S13.

^cIsotopic abundance measurements: Table S5.